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  1. #13
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    Default Re: work with what you got build

    Lots of failures to enjoy here!


    I did end up with a working part. Please comment if you have any questions.





  2. #14
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    Default Re: work with what you got build

    The gantry looks pretty wimpy compared to the rest of the build. Also, does it only have a single profile rail? Those are rated for some torque on them, but not much, really should double up (if there isn't another hiding somewhere.)
    Also the bed could probably use some bracing, but you mentioned that's temporary anyway.
    That type of spindle is pretty light duty. I've seen some of that general type that are just a motor with an ER collet holder pressed on one shaft and a fan on the other. No precision/preloaded bearings, tons of runout and a spindly little shaft. Looks like the one you've got is a step or 2 up from those, but still lots of room for improvement there.



  3. #15
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    Default Re: work with what you got build

    Quote Originally Posted by skrubol View Post
    The gantry looks pretty wimpy compared to the rest of the build. Also, does it only have a single profile rail?
    .
    it is surprisingly stiff but I have more of the 4" steel stock to replace it with if things keep improving. I can do some testing if anyone wants to know the practical stiffness of the current 2.5" x .25" aluminum square tube setup. This is much more stiff than c-beam.

    Quote Originally Posted by skrubol View Post
    Those are rated for some torque on them, but not much, really should double up (if there isn't another hiding somewhere.)
    good eye. Yup it only has one rail. I have a SBR16 mounted on the back however I couldn't see how a single SBR rail would help in the position it is in. I just left it unattached and it does provide some support to the gantry beam. I may install the 2nd 1000mm rail where the SBR16 is on the back, but I may just wait till I get the larger 4" x .25" installed. It is getting quite heavy though and if it falls over it may never get back up. If it falls over on me I may never get back up.
    Quote Originally Posted by skrubol View Post

    Also the bed could probably use some bracing, but you mentioned that's temporary anyway.
    .25" steel should be pretty stiff no? The aluminum beds I've seen seem much less robust unless I am milling something about the strength of extrusion.

    I can drop the bed about 7 more inches. I'd like to have my vice semi-permanantly installed and be able to plop something on top for larger flast stock like MDF/plywood. The problem with that is that I believe the lower I drop my spindle the less rigid my setup is with the Z rails in motion. The really ideal setup is to have the vice as close to the Y gantry as I can get it.

    Quote Originally Posted by skrubol View Post

    That type of spindle is pretty light duty. I've seen some of that general type that are just a motor with an ER collet holder pressed on one shaft and a fan on the other. No precision/preloaded bearings, tons of runout and a spindly little shaft. Looks like the one you've got is a step or 2 up from those, but still lots of room for improvement there.
    Yup, I have a thread going in the spindle section and I am now looking to get something with angular contact bearings. The spindle is pretty good at running adaptive cuts but it does not like slot cutting at all and 2d contours need to be limited to .2mm doc or less. The runout is as bad as .044mm



  4. #16
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    Default Re: work with what you got build

    If you can fit a rail on top without getting in the way of your screw, that is a fairly common way to mount a second rail, it's often better than 2 rails on the front, but harder to align.

    You definitely don't want more room between the bed and the gantry than you need. You're right that longer Z extension is bad (not only does it add more opportunity for flex in the Z, it will want to twist the gantry more.) Stiffness is the square of thickness (all else equal,) so .25" steel isn't super stiff compared to something with a frame, but it's mostly a lack of stiffness in the Z axis, where it's probably least likely to show. Also if your vise is bridging most of the space between the rails that will stiffen things up as well. Aluminum extrusions can be quite stiff, but most of the machines made out of the thinner stuff are pretty wimpy.

    I'll take a look at your spindle thread as well.

    Machine certainly performs better than it looks!



  5. #17
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    Default Re: work with what you got build

    Quote Originally Posted by skrubol View Post
    If you can fit a rail on top without getting in the way of your screw, that is a fairly common way to mount a second rail, it's often better than 2 rails on the front, but harder to align.

    You definitely don't want more room between the bed and the gantry than you need. You're right that longer Z extension is bad (not only does it add more opportunity for flex in the Z, it will want to twist the gantry more.) Stiffness is the square of thickness (all else equal,) so .25" steel isn't super stiff compared to something with a frame, but it's mostly a lack of stiffness in the Z axis, where it's probably least likely to show. Also if your vise is bridging most of the space between the rails that will stiffen things up as well. Aluminum extrusions can be quite stiff, but most of the machines made out of the thinner stuff are pretty wimpy.

    I'll take a look at your spindle thread as well.

    Machine certainly performs better than it looks!
    I ended up buying a .8kw motor with 2 pairs of 7002 bearings and a HY 1.5kw vfd. That should add about 3 lbs to my y/Z setup which is already very heavy.

    I have ~700 mm of X rail but only around 400 of actual travel ( I can space my X rail block closer to improve this a bit if I want.). Effective Y travel is ~790mm. I have some lengths of .125" square tube I could weld a frame with however my welding skills took a 20 year break and did not come out the other end with much left.

    For the bed what inexpensive options do I have that I can fabricate? If you could direct me to threads with good beds that would be helpful.



  6. #18
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    Default Re: work with what you got build

    I wouldn't worry too much about 3lbs on the Z, cutting forces are likely much higher, and static forces are easier to deal with than dynamic forces. May need to put some a tension spring or something to help the Z axis stepper if it starts stalling.

    Even bolting a couple square or rect tubes to the plate between the carriages can help a bit. I'm not sure on 'next step' beds that won't blow the budget. I'm in a similar (though bigger) situation, I've got the bones of a router (PCB drilling machine actually,) that has a very light duty frame for a table that I'm going to throw some aluminum tooling plate on to get it up and running, but I'm probably going to end up eventually getting a VMC table off ebay and having to spend more on freight than on the table. It'll probably be the most expensive single part of the build.



  7. #19
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    Default Re: work with what you got build

    My new spindle was supposed to arrive today. They UPS hit me with a weather disruption delay....

    Made a pcb this evening with flatcam.

    watching this is really thrilling stuff.




    if anyone is interested in flatcam and easyeda I'm happy to provide details.



  8. #20
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    Default Re: work with what you got build

    Mounting plate for new spindle. I'm planning on using a clamping method and I was wondering what folks think about that vs just bolting through the flanges on the spindle mount?



    work with what you got build-20180923_132616-jpg

    Attached Thumbnails Attached Thumbnails work with what you got build-20180923_132616-jpg  


  9. #21
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    Default Re: work with what you got build

    Here is the new spindle mounted. I was a bit concerned that it sounded like a cat in a garbage disposal on the first 3 passes. I had checked the runout with an indicator good for .002 mm and it looked like about 0.001mm runout. Turned out the spindle was running backwards. Doh! I flipped it to rev (actually running forward) and it worked ok for a few passes. I'm going to get the z limit hooked back up, install the rest of the clamp screws, tram it and video some test cuts.

    The mount is 0.25" steel plate with the surface which mate to the 20mm linear rails machined. The other side was really quite flat so I didn't bother face milling it. The cheap spindle clamp is friction clamped via 2 30mm aluminum blocks with M5 screws spaced at 30mm and tapped into the steel plate. I hope this makes tramming it and adjusting the height a bit easier than drill/tap through the spindle mount flange directly.







    work with what you got build-20180924_190206-jpg

    Attached Thumbnails Attached Thumbnails work with what you got build-20180924_190206-1-jpg   work with what you got build-20180924_190206-jpg  


  10. #22
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    Default Re: work with what you got build

    I swapped a pair of the spindle wires and fixed my running backwards problem. I did a few small gears for a TT motor out of aluminum documented below. Keep in mind i'm only running on a single 20mm rail on the Y axis and 2.5 x .25" aluminum square tube. I'm very happy with the surface finish and the new spindle. My current issues are:

    1. VFD is loud! I have it wired to a plug now and I think I need to get a switch setup. Anyone have advice on making the VFD silent?

    2. I'm still not sure how to do the table have it waterproof, flat, and keep the weight down. I want a quick and easy way to get the vice installed and or a way to keep it installed. I'm thinking a deck above it for large flat stock.

    3. I need to redo the Y Gantry with the 4" steel square tube. I'm scared to mill it. How much can you mill off a square tube before you cause issues with the tension? I had tried a 1.5mm cut previously and it bowed about 5mm.

    4. I need to make an enclosure once I make the frame attachments permanent.

    5. The DRV8825's and GRBL board are doing very well. Long term I'd like to make a pcb for g2core and run a 32bit processor but it works pretty well and if it ain't broke!? Anyone have ideas on how worth the effort g2core is? On a side note I"m running klipper firmware on my 3d printer and wow does it make it go fast. I wonder if the klipper approach would also help cnc machines with 8 bit processors?

    6. The vise I have on there is garbage. Once I get the table figured out I need to relegate that POS to the drill press.

    7. I'm a bit concerned about my compressor's ability to keep up. I also bought a solenoid to control the air and I was thinking of a 50% duty cycle of fast air pufs vs a steady stream of air. Has anyone tried this approach?







  11. #23
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    Default Re: work with what you got build

    Dust Collection!work with what you got build-20180926_190530-jpg

    that color is loud huh?

    Attached Thumbnails Attached Thumbnails work with what you got build-20180926_190530-jpg  


  12. #24
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    Default Re: work with what you got build

    first dust shoe had an issue, this one is working well.

    https://www.thingiverse.com/thing:3124279



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